Definition of relative humidity

Question 1

What are the typical weather conditions in a westerly situation?

Answer 1

Very changeable

Question 2

Where is the core of the polar front jet stream found?

Answer 2

In the tropical air mass

Question 3

At what geographic latitude are prevailing westerlies found

Answer 3

40-60 // average 50

Question 4

In a low pressure system, convergence at the surface is caused by

Answer 4

Frictional forces

Question 5

What can favour the development of frontal fog?

Answer 5

Increase of relative humidity by evaporation of rain drops

Question 6

What weather would you expect from a cold front?

Answer 6

Initially lifts warm air causing thunderstorms and CB clouds. Pressure drops then rises. After front passes, cool temperatures and clear or mild sky

Question 7

Occluded front weather

Answer 7

There is often precipitation from CB and NS clouds. Wind changes direction as front passes and temp changes. Usually dry and clear skies after it passes

Question 8

The easterly jet is a jet stream that occurs

Answer 8

Only in the summer of the northern hemisphere at approximately 45000 feet when the ITCZ is at it’s most northerly position

Question 9

Insolation as at a maximum at

Answer 9

local noon

Question 10

Clear ice is forms by

Answer 10

supercooled drops hit the aircraft and slide back on the airframe, freezing slowly. Hard to remove and hazardous. 0’ to -15’

Question 11

Rime Ice

Answer 11

Freezes on impact, thick frost appearance. -10° to -20°

Question 12

Mixed ice

Answer 12

Mixture of rime and clear. -10° to -15°

Question 13

Hoar frost

Answer 13

When body of aircraft is very cold and freezes ambient moisture

Question 14

How to avoid high concentrations of ice crystals

Answer 14

Plan ahead and fly in UPWIND direction

Question 15

Describe trade winds

Answer 15

Low level wind system between subtropical high pressure belt and the equatorial trough of low pressure

Question 16

How does lightning affect aircraft?

Answer 16

Can cause some structural damage. Aircraft can become a charge carrier and initiate an electrical discharge

Question 17

What is a cold air drop?

Answer 17

A low pressure area with colder air compared to its surroundings. It can be found on upper contour charts

Question 18

Water vapour condensing into water (heat) -

Answer 18

Releases large amounts of latent heat

Question 19

The cloud sequence of approaching warm front

Answer 19

CI, CS, AS, NS, ST

Question 20

What wind change is expected in northern hemisphere when descending to surface?

Answer 20

Backing ca. 30 degrees, speed is reduced by ca 50%

Question 21

Divergence over a uniform surface is caused by:

Answer 21

Frictional force + anticyclonic curvature of the isobars

Question 22

How can orographic fog be dissipated?

Answer 22

Downslope wind

Question 23

The ITCZ is further North or South in summer?

Answer 23

Further north in summer

Question 24

In towering cumulus clouds, what features does the cloud have in terms of vertical wind and temperature in relation to the environment

Answer 24

Strong updraughts occur and temperature inside the cloud is higher than surrounding areas

Question 25

Furthest north ITCZ reaches in summer is ?

Answer 25

China

Question 26

Characteristics of the Bora are?

Answer 26

Cold and strong wind that blows in winter towards the Adriatic

Question 27

What happens physically in a warm occlusion?

Answer 27

The warm air is lifted

Question 28

Where are easterly waves most likely to form?

Answer 28

In the trade wind zones

Question 29

What temperatures would you expect the worst icing effects?

Answer 29

between -20°C and -30°C

Question 30

Cumulonimbus cloud with clearly defined anvil is:

Answer 30

Capillatus

Question 31

A blocking anticyclone in the northern hemisphere is:

Answer 31

A quasi-stationary, warm anticyclone situated between 50°N and 70°N

Question 32

Area of thermal low pressure is formed by:

Answer 32

A temperature rise in an area in relation to the environment

Question 33

What could be said about the height of a polar front jet stream core

Answer 33

It lies at a height where there is NO horizontal temperature gradient

Question 34

When is latent heat absorbed?

Answer 34

Changing from solid to liquid

Question 35

What is the role of the World Area Forecast Centre (WAFC)

Answer 35

A meteorological centre that provides real-time meteorological information broadcasts for aviation

Question 36

Does the wind veer or back upon the passage of a front in the northern hemisphere?

Answer 36

Veers when front passes

Question 37

Depressions associated with developing frontal waves move in the direction of the 3000 feet wind in

Answer 37

The warm sector

Question 38

The height of the lifting condensation level is determined by :

Answer 38

The temperature and dew point at the surface

Question 39

What is classed as a low level cloud?

Answer 39

SC (stratocumulus)

Question 40

A parcel of rising air rises through an isothermal layer. What happens to the temperature?

Answer 40

It remains constant

Question 41

How do you recognise a cold air pool?

Answer 41

As a low pressure area aloft (e.g on the 500 HPA chart)

Question 42

What weather would you expect a foehn wind to bring in the Northern Alps?

Answer 42

Turbulence during south foehn

Question 43

What would you expect if a cold surface is covered by a warm air mass?

Answer 43

A ground inversion will develop

Question 44

What weather is encountered during summer, over land, in the centre of a cold-air drop?

Answer 44

Showers and thunderstorms

Question 45

A Foehn wind occurs on the:

Answer 45

Leeward (downwind) side of a mountain range and is caused by significant moisture loss by precipitation from cloud

Question 46

Why are there few or no clouds in high pressure areas?

Answer 46

Due to subsiding winds

Question 47

What weather phenomenon is created by valleys and mountain slopes?

Answer 47

Valley inversions

Question 48

The weather behind a cold front is typically

Answer 48

Cu cloud, noticeably colder and drier than the air in front

Question 49

What type of cloud seen from long distance could indicate a tropical revolving storm

Answer 49

Dense CI

Question 50

How long does a typical frontal depression last in Europe?

Answer 50

7-10 days

Question 51

An isohypse (contour) indicates

Answer 51

The true altitude of a pressure level

Question 52

Regarding jet stream turbulence, the strongest CAT is expected to be found on :

Answer 52

The cold air side of the pool

Question 53

What type of frozen precipitation with a diameter of less than 4mm can be used in a METAR?

Answer 53

Ice pellets

Question 54

Evaporation absorbs or releases heat?

Answer 54

Evaporation absorbs heat

Question 55

Define a "HIGH"

Answer 55

An area of higher pressure than that of the horizontal environments

Question 56

Pressure compared to sea level formula

Answer 56

FL200 = 50% | FL400=25%

Question 57

Frontal thunderstorms are mainly associated with:

Answer 57

Cold fronts

Question 58

At which latitudes are you most likely to find the subtropical high pressure belt?

Answer 58

Sub-tropical highs are centred at around 25°-35°

Question 59

Rainy seasons in equatorial Africa

Answer 59

March to May and October to November

Question 60

The predominant pressure systems in the North Atlantic during summer are:

Answer 60

Azores High and Weak Low over NE Canada

Question 61

Prevailing winds in coastal West Africa are

Answer 61

SW monsoon in summer and NE trade winds in winter

Question 62

The Harmattan is:

Answer 62

NE wind affecting NW Africa during November to April which causes reduced visibility due to dust

Question 63

A trough near the surface is an area of ? pressure and ? features :

Answer 63

Convergence and widespread ascent

Question 64

Under anticyclonic conditions in the northern hemisphere, with curved isobars the speed of the gradient wind is :

Answer 64

Greater than the geostrophic wind

Question 65

What change of state RELEASES latent heat?

Answer 65

Liquid to solid

Question 66

The family of medium clouds include altos and nimbostratus. Where would you expect their height of base to range from?

Answer 66

6500 - 23000 feet

Question 67

The main icing zone in the ITCZ is between FL:

Answer 67

FL 160 - FL260

Question 68

In wintertime, stratus is often formed when warm maritime air moves over cold land. How could this cloud be classified?

Answer 68

Turbulence cloud

Question 69

The RVR reported in the METAR is always the:

Answer 69

Value representative of the touchdown zone

Question 70

What weather would you expect BEHIND a cold front?

Answer 70

Scattered cloud cover and showers

Question 71

Where do the trade winds blow?

Answer 71

Between the horse latitudes and the doldrums

Question 72

What type of weather does coalescence produce in mid latitudes?

Answer 72

Drizzle or light rain

Question 73

Coalescence definition:

Answer 73

Colliding of rain drops

Question 74

When a cold front passes a chain of mountains, it's activity

Answer 74

Strengthens upwind of the mountains

Question 75

Tropical storm affecting North Australia is called ? and occurs in ?

Answer 75

Cyclone and occurs December - April

Question 76

In which stage of a thunderstorms life cycle do up draughts and downdraughts occur simultaneously?

Answer 76

Mature Stage

Question 77

STATEMENT - Cold air over warm sea can provide lifting action for air mass T-storms

Answer 77

STATEMENT - Cold air over warm sea can provide lifting action for air mass T-storms

Question 78

Snow grains fall from :

Answer 78

Stratus or supercooled fog

Question 79

What type of cloud is associated with snow showers?

Answer 79

Cumulus or Cumulonimbus

Question 80

The main substance in cirrostratus clouds is :

Answer 80

Ice Crystals

Question 81

Most tornadoes have wind speeds of :

Answer 81

20 - 40 Knots

Question 82

What units are used to report vertical windshear?

Answer 82

KT/100ft

Question 83

Thunderstorms are NOT usually associated with :

Answer 83

Warm fronts

Question 84

Describe a warm occlusion in terms of relative position of warmest and coldest air

Answer 84

The coldest air mass is AHEAD of the original warm front

Question 85

What climate type is to be expected at 10N - 20N (equatorial)

Answer 85

Tropical rain climate

Question 86

The typical weather conditions affecting Darwin in July is?

Answer 86

Dry season, mainly SE winds and visibility reduced by haze and dust

Question 87

Which jet would affect a flight from around UK to India during January?

Answer 87

Sub-tropical westerly jet with wind speeds exceeding 90 knots

Question 88

When is the term CAVOK used?

Answer 88

Visibility of 10KM or more, no clouds below 1500M (5000ft) and no CU clouds or anything of significance

Question 89

What is a VOLMET broadcast?

Answer 89

Repetitive voice broadcast including METAR, TAF SPECI and SIGMET

Question 90

What type of cloud can give freezing rain?

Answer 90

NIMBOSTRATUS, especially in advance of a warm front

Question 91

What is a downburst?

Answer 91

Concentrated downdraught with High speeds and LOWER temperature than surrounding air

Question 92

System that REDUCES in intensity with increasing height must be :

Answer 92

Cold and high pressure as it is concentrated at lower levels

Question 93

Characteristics of a warm occlusion in terms of air being warmer/colder behind/in front of the warm sector

Answer 93

Air behind the occlusion is WARMER than air in front

Question 94

Up to what FL can one expect mountain waves?

Answer 94

FL 600

Question 95

What imaging can be used to detect top of cumulonimbus clouds?

Answer 95

Visual and infra red imaging

Question 96

Most likely weather as a warm front passes is :

Answer 96

Moderate continuous rain, intermittent light drizzle

Question 97

Where is the source of the southwest monsoon?

Answer 97

The southern hemisphere

Question 98

What could be said about nimbostratus clouds and their tendency to extend into multiple layers?

Answer 98

It IS possible for NS clouds to extend into more than one layer

Question 99

A possible trigger for an air mass thunderstorm is:

Answer 99

Intense insolation of a land surface in the area of a col or a weak low